The present invention relates to a method for mechanical decontamiation of contaminated surfaces of mineral materials, in particular concrete surfaces and masonry. Although the application of the method or the use of the device according to the invention is mainly concerned with radioactively contaminated surfaces, the method as well as the device is indeed suitable for decontaminating contaminated surfaces of mineral materials by removal of a contaminated layer. In particular here one envisages masonry and ground surfaces in and around the reactor building, however one also considers walls or ground which is PCB contaminated, or simply also concrete surfaces and masonry smeared with paint.
There are known methods and devices for cleaning radioactive surfaces of materials based on cement or concrete and of masonry with which one mechanically removes the contaminated locations in that one manually grinds away the surface by machine. For this in particular the publication “Strahlschutzaspekte bei radioaktiven Kontamination” (Radiation protection aspects with radioactive contamination) by A. Etzweiler et al. is referred to, which appeared on the occasion of the 17th annual meeting of the “Fachverband für Strahlenschutz” e.V. from 8 Jun. 1983-10 Jun. 1983 in Aachen. The completely dry, purely mechanical cleaning methods described here all effect a great creation of dust, and at the same time the shown expense with regard to apparatus is large. The quantity of dust occuring with these methods leads to a large problem of contamination, wherein the already cleaned walls are practically recontaminated, if only to a lesser extent. Accordingly the surfaces must be machined several times and there arises a great amount of material to be disposed of. In particular with radioactively contaminated surfaces one seeks methods by way of which the quantity of waste is reduced as much as possible since this waste must be disposed of according to national regulations. The disposal of radioactive material is accordingly extremely expensive.
As is known the radioactive contamination is limited essentially to the surface or to the region close to the surface. Based on this recognition one has selected methods which typically are for a low removal depth, specifically in particular grinding or machining methods. As previously mentioned, these two methods however have the disdvantage that they set free large quantities of dust. The dust occuring at the same time is extremely fine and accordingly is difficult to filter. Accordingly also large efforts must be made in order to be able to safely vacuum and filter out this fine dust, which again considerably increases to secondary waste which this entails. This matter becomes a particular problem when the suctioned air must additionally be washed.